Everyone thinks General Motors has too many cars for too many brands, and everyone is right. Moreover, cars like this one have fallen out of favor - mostly because those who want to go bigger also go taller, heavier, and truckier - but if there's still a place in our landscape for whopper sedans, you've got to admit that Buick is a fitting place for one to go.GM is improving the case for its stay. In a move that helped everybody, they dropped its Pontiac Bonneville brother, reducing this "G-body" platform of cars (first set in motion by the Oldsmobile Aurora) to a more manageable two-member family, the more expensive being the new Cadillac DTS. Buick finds further favor in the decision to consolidate the former LeSabre and Park Avenue into a new sedan called Lucerne, which, if you shop at Safeway, might lead you to conclude that this new Buick is as safe as milk.It should at least go down easy. Buick's average buyer - now 68 - doesn't like surprises, and he will find lots of familiar parts to go along with the proven platform, such as the 3800 V6 engine, 4-speed automatic transmission, most of the dimensions, and restrained styling. But several things elevate this beyond a simple rehash-and-rename job.